Agronomic biofortification is one of the approaches which have been successfully adopted for improving the nutritional content of plant-based foods and is mainly focused on optimizing the application of mineral fertilizers and/or the improvement of the solubilization and mobilization of mineral elements in the soil. In general, mineral elements with a good dynamism in the soil and in the plant are good candidates for a prosperous agronomic biofortification. Selenium deficiency occurs in areas where soil Se is low, including parts of Europe, China, North America, Australia, New Zealand, and Southern Africa. Selenium toxicity occurs in areas where soil Se is naturally high, including areas of China, India, and the United States. Toxicity from naturally occurring Se may be intensified by irrigation of seleniferous soils, mining, and use of Se-rich fossil fuels. Then, management practices benefit from a thorough understanding of the mechanisms of plant Se uptake and the fate of Se in different plant species.
After its discovery, selenium was most noted for its harmful effects. Selenium was the first element identified to occur in native vegetation at levels toxic to animals. Poisoning of animals can occur through consumption of plants containing toxic levels of selenium. Livestock consuming excessive amounts of selenized forages are afflicted with “alkali disease” and “blind staggers”. Typical symptoms of these diseases include loss of hair, deformed hooves, blindness, colic, diarrhoea, lethargy, increased heart and respiration rates, and eventually death. On the other hand, selenium deficiency in animal feeds can cause “white muscle disease”, a degenerative disease of the cardiac and skeletal muscles. In this regard, this review paper attempts to summarize the essentiality of selenium for humans, animals, and plants and the role of selenium in plant metabolism and physiology.
Humans and animals require a multitude of nutrients in order to have a properly functioning body for purposes of growth, development and metabolism. Plant-based foods have represented one of the most important nutrient sources in human diet since the beginning of mankind. But nowadays the amount of arable land is being reduced and much of the natural resources already in use show signs of degradation. Also, staple crops (i.e. plants that constitute the main food in the diets of people in developing countries, e.g. wheat, rice, maize, and cassava) regrettably contain low amounts of micronutrients, making them insufficient to meet the minimum daily requirements. Shortages in mineral micronutrients, including iron (Fe), zinc (Zn), selenium (Se), and iodine (I), are affecting more than half of the world’s population. In this case, it is fundamental to improve strategies that let us make plant foods more efficient and with higher micronutrient amounts and bioavailability concerning their edible textures. In this regard, in this review paper, we tried to summarize selenium availability and its application in the soil, plant and food systems to understand the place of selenium in plant-based foods.
Selenium (Se) is an essential micronutrient, and the ability of some crops to accumulate Se is crucial for human and animal nutrition and health. Se deficiency can cause white muscle disease characterized by muscle weakness, heart failure, unthriftiness, and death in livestock. This study was undertaken to investigate the effect of sulphur (S) on Se concentration in alfalfa (Medicago sativa L. cv. Verko) as a nonhyperaccumulator plant. Alfalfa plants grown in the field were treated foliarly with 3 g Se ha−1 solutions of selenate, 3 g S ha−1 sulphate, and both. The concentration of Se in both the leaves and stems of plants was similar in the control and S-treated plants. Se concentration in plants treated with S was undetectable, as expected. S was shown to enhance Se accumulation in alfalfa. Furthermore, although foliar Se + S spray increased biomass, photosynthetic pigments decreased peroxidase activity and malondialdehyde content. Overall, results suggested that foliar Se + S spray can be applied as a biofortification to improve alfalfa plants with appropriate amounts of Se and better nutritional as well as functional quality.